Duvergertörvény

Duvergertörvény, also known as Duverger's Law, is an observation in political science that links a country's electoral system to its party system. Attributed to French sociologist Maurice Duverger, the law posits that plurality (first-past-the-post) electoral systems tend to result in a two-party system, while proportional representation systems tend to produce multiparty systems.

The reasoning behind this observed correlation is that under a plurality system, voters are incentivized to vote for the candidate most likely to win, rather than their preferred candidate who has little chance of success. This phenomenon, often referred to as the "strategic vote," discourages smaller parties from gaining traction and can lead to the consolidation of support around the two largest parties. Conversely, proportional representation systems, which allocate seats based on the overall percentage of votes received by each party, allow smaller parties to gain representation and encourage a wider range of political viewpoints to be expressed.

While Duverger's Law is a widely cited principle, it is important to note that it is an empirical observation rather than a strict causal law. Other factors, such as historical context, social cleavages, and the specific rules of an electoral system, can also influence the number of parties in a political system. Nevertheless, Duverger's Law remains a foundational concept for understanding the relationship between electoral rules and party competition.